"What Lies Below" isn't half-bad as an icky take on "My Hot Stepfather is a Monster" formula

What Lies Below (2020)

“What Lies Below” finally answers the question, “What if your mom’s hot new boyfriend was a horny lake monster?” What initially seems like a girl-who-cried-wolf thriller, like 1987’s “The Stepfather” or some lesser Lifetime erotic thriller, eventually copulates with “Species,” except replace Natasha Henstridge with the male half of a Harlequin romance cover come to life. Making his feature debut, writer-director Braden R. Duemmler builds a simmering lust and takes some big, batty, even icky swings toward an admirably mean ending. Not to be confused with 2000’s Michelle Pfeiffer-Harrison Ford suspenser “What Lies Beneath,” “What Lies Below” isn’t half-bad, even if its silly premise is played with earnest faces.

When pure, awkward teenager Liberty (Ema Horvath) gets picked up by her mother, Michelle (Mena Suvari), from archaeology camp, she is more than a bit blindsided when they arrive at their lakeside cabin in the Adirondack Mountains. Coming to shore in a Speedo is John (Trey Tucker), Michelle’s hunky live-in boyfriend who also happens to be an aquatic geneticist completing his research with some fresh water finds. “Libby” can’t help but ogle Mom’s new beau, until she notices John’s very strange behavior, like wringing out his own sweat to drink it and having a weird focus on the parasites he keeps in his makeshift lab in the basement. That is just the tip of the iceberg, though, once they have an inappropriate encounter and then Libby spots John wading into the lake toward a red underwater light. Of course, John asks Michelle to marry him, but how can Libby tell her mom that John is not the perfect soon-to-be stepfather or even human?

What does lie below is generally pretty clear—and why Michelle begins to feel sick—but that doesn’t really stop “What Lies Below” from sinking our interest. 28-year-old Ema Horvath (2020’s “The Mortuary Collection”) is compelling to watch and convincing as a teenage girl full of so many different emotions as she undergoes a sexual awakening. After Horvath and Mena Suvari communicate a codependent mother-daughter relationship that sometimes feels more like a friendship, Suvari does get sidelined, and for a fun little bonus, every time she calls Libby “baby girl,” drink! The frequently topless Trey Tucker handsomely fills the part of John Smith and pulls off the balance of seductive smoldering and snarling menace. For his first feature, Duemmler crafts a cleanly shot package with composer Gavin Keese’s John Carpenter-esque score quite propulsive, and he wisely holds back (maybe for budgetary reasons) from showing John’s true form from head to toe in full creature-feature fashion. Once the “what” is more or less revealed without being explicit, “What Lies Below” sees itself out abruptly, but it still does not cop out on the grim resolution.

Grade: C +

Vertical is releasing “What Lies Below” (87 min.) on video on demand and digital on December 4, 2020.